鸡胃肠道生长抑素(SS)mRNA表达的组织特异性

以30dArborAcre(AA)肉鸡为模型,采集胃肠道样品,采用相对定量RT-PCR方法研究了生长抑素(SS)mRNA在鸡胃肠道分布的组织特异性。结果表明,腺胃SSmRNA的表达量高于所有肠段,差异极显著(P<0.01);十二指肠和空肠SSmRNA的表达丰度相似,二者均显著高于回肠(P<0.05)。定性研究显示,肌胃和结直肠均有SSmRNA表达,但其表达量显著低于腺胃、十二指肠、空肠和回肠。SSmRNA在主要的消化(腺胃)、吸收(十二指肠和空肠前段)器官的高丰度表达,提示SS对营养物质的消化吸收具有重要的调控作用。异性     

Zinc absorption from low phytic acid genotypes of maize (Zea mays L.), Barley (Hordeum vulgare L.), and Rice (Oryza sativa L.) assessed in a suckling rat pup model

Dietary phytic acid is a major causative factor for low Zn bioavailability in many cereal- and legume-based diets. The bioavailability of Zn in seed of low phytic acid (lpa) variants of maize ( Zea mays L.), rice ( Oryza sativa L.), and barley ( Hordeum vulgare L.) was evaluated using a suckling rat pup model. Suckling rat pups (14 days old, n = 6-8/treatment) were fasted for 6 h and intubated with (65)Zn-radiolabeled suspensions prepared using seed produced by either wild-type (normal phytic acid) or lpa genotypes of each cereal. Test solutions were radiolabeled overnight (all genotypes) or immediately prior to intubation (barley genotypes). Pups were killed 6 h postintubation and tissues removed and counted in a gamma counter. Zn absorption was low from wild-type genotypes of maize (21, 33%) and rice (26%), and phytic acid reduction resulted in significantly higher Zn absorption, 47-52 and 35-52%, respectively. Zn absorption from wild-type barley incubated overnight was high (86-91%), and phytate reduction did not improve Zn absorption (84-90%), which is likely due to endogenous phytase activity. When the wild-type barley solutions were prepared immediately before intubation, Zn absorption was significantly lower (63, 78%) than from the lpa cultivars (92, 96%). Variation in seed or flour phenolic acid levels did not affect Zn absorption. Differences in seed Zn levels did not substantially affect Zn absorption. Thus, when phytic acid is abundant in a diet, it has a larger effect on Zn absorption than the level of Zn. Therefore, reducing the phytic acid content of staple cereal grains may contribute to enhancing Zn nutrition of populations consuming these staple foods.     

仔猪水通道蛋白基因的克隆及断奶应激对其在胃肠道组织mRNA表达的影响

水通道蛋白(AQP)作为一种膜转运蛋白,对于调控肠道组织的水分子转运具有重要作用。本实验利用同源序列克隆法设计引物,从仔猪(Susscrofa)的消化道组织中克隆AQPs家族基因(AQP2~AQP11)(GenBank登录号分别为EU636238、EU161094、EU165525、EU192130、EU620575、EU024116、EU220426、EU220427、EU582021和EU220425),并对其进行生物信息学分析。采用荧光定量PCR研究断奶应激对于仔猪胃肠道组织中AQP1、AQP3、AQP8和AQP11的mRNA表达影响。生物信息学分析发现,猪AQPs家族基因含有高度保守的天冬酰氨-脯氨酸-丙氨酸(NPA)结构序列,基因表达分析发现,断奶组仔猪的AQP1基因在十二指肠、回肠和结肠组织的mRNA表达量与对照组相比显著上调(P<0.05);AQP3基因在胃和小肠组织的mRNA表达有显著上调(P<0.05);AQP8基因在胃和回肠组织中mRNA表达有显著上调(P<0.01),在其他组织中没有显著差异;AQP11基因在空肠组织的mRNA表达量显著上调了1.7倍(P<0.05)。这些研究结果表明,AQP基因可能在断奶应激引起的仔猪肠道腹泻中发挥重要作用。     

Genetic selection for enhanced bioavailable levels of iron in bean (Phaseolus vulgaris L.) seeds

The bioavailability of Fe from 24 select genotypes of bean (Phaseolus vulgaris L.) seeds containing a range of concentrations of Fe, myo-inositol pentaphosphate plus phytic acid (IP5+IP6), and tannins was studied using a rat model. Bean accessions, selected from field trials for their variations in Fe, phytate, and tannin seed concentrations, were grown in a greenhouse in nutrient solutions radiolabeled with (59)Fe. Mature seeds were autoclaved and lyophilized. Test meals (containing 1 g of dried bean, 0.5 g of sucrose, and 1 g of basal Fe-deficient diet) were fed to marginally Fe-depleted weanling rats over a 3-h period; rats were radioassayed in a gamma-spectrometer immediately after feeding and daily thereafter for the next 10 d. Radioiron retention data were used to calculate percent Fe absorption (i.e., Fe bioavailability) from the meals. Seed Fe concentrations ranged from 52 to 157 microg g(-)(1) dry weight. There was a tendency to also select for higher Zn concentrations in the beans when selecting for high Fe concentrations. The Fe bioavailability to rats from test meals depended on the genotype and varied from 53% to 76% of the total Fe. Bean genotypes with higher seed Fe concentrations resulted in increased amounts of bioavailable Fe to rats. There was no significant correlation between the Fe concentration in different bean genotypes and Fe bioavailability to rats attributable to variations in IP5+IP6 or tannins, even though these antinutrients varied widely (i.e., from 19.6 to 29.2 micromol of IP5+IP6 g(-)(1) and from 0.35 to 2.65 mg of tannins g(-)(1)) in the test meals. Other unknown seed factors (i.e., antinutrients or promoter substances) may be contributing factors affecting Fe bioavailability from bean seeds.     

Protection by polyphenols of postprandial human plasma and low-density lipoprotein modification: the stomach as a bioreactor

Recent studies dramatically showed that the removal of circulating modified low-density lipoprotein (LDL) results in complete prevention of atherosclerosis. The gastrointestinal tract is constantly exposed to food, some of it containing oxidized compounds. Lipid oxidation in the stomach was demonstrated by ingesting heated red meat in rats. Red wine polyphenols added to the rats' meat diet prevented lipid peroxidation in the stomach and absorption of malondialdehyde (MDA) in rat plasma. In humans, postprandial plasma MDA levels rose by 3-fold after a meal of red meat cutlets. MDA derived from meat consumption caused postprandial plasma LDL modification in human. The levels of plasma MDA showed a 75% reduction by consumption of red wine polyphenols during the meat meal. Locating the main biological site of action of polyphenols in the stomach led to a revision in the understanding of how antioxidants work in vivo and may help to elucidate the mechanism involved in the protective effects of polyphenols in human health.     

Eisenia fetida growth inhibition by amended activated carbon causes less bioaccumulation of heavy metals

Purpose

Activated carbons (ACs) were applied to evaluate the effects of surface oxidation on bioavailability and bioaccumulation of cadmium (Cd) and copper (Cu) in freshwater sediment along with Eisenia fetida biomass change.

Materials and methods

A modified sequential extraction procedure was conducted to measure the changes in bioavailable fractions of heavy metals 6 weeks after the addition of nitric acid-oxidized AC. Bioaccumulation of heavy metals in E. fetida was analyzed after 2 weeks of exposure to AC-amended contaminated sediments. Changes in biomass of earthworms caused by AC amendments were observed over 2 weeks of exposure to clean sand.

Results and discussion

Surface oxidation of AC caused little impact on AC surface properties except for oxygen contents leading to enhanced sorption capacity for heavy metals. Bioavailable fractions of the heavy metals increased after 6 weeks, and less was bioavailable with various ACs than without AC. The earthworms were exposed to the sediments mixed with ACs for 6 weeks. After 2 weeks of exposure, bioaccumulation of Cd and Cu decreased drastically. More than 76 % of Cd and 80 % of Cu reductions were observed with each type and dose of AC. Weight loss of E. fetida incubated in clean sand for 13 days after AC amendments was observed, but was not affected by surface oxidation.

Conclusions

Inhibited growth of E. fetida due to AC could be responsible for the reduced bioaccumulation of Cd and Cu in the earthworms as AC inhibited the movement of earthworms, leading to less bioturbation and decreased consumption of nutrients.     

Effect of simultaneous consumption of milk and coffee on chlorogenic acids' bioavailability in humans

Different studies have shown that milk may interact with polyphenols and affect their bioavailability in humans. The present study investigated the effect of the simultaneous consumption of coffee and milk on the urinary excretion of chlorogenic acids (CGA) and metabolites. Subjects were submitted to consumption of water, instant coffee (609 mmol of CGA) dissolved in water, and instant coffee dissolved in whole milk. Urine was collected for 24 h after consumption of each treatment for analysis of CGA and metabolites by HPLC/LC-MS. The amount of CGA and metabolites recovered after consumption of combined coffee-milk (40% ± 27%) was consistently lower in all subjects compared to that of coffee alone (68% ± 20%). Concluding, the simultaneous consumption of milk and coffee may impair the bioavailability of coffee CGA in humans.     

Fate of anthocyanins and antioxidant capacity in contents of the gastrointestinal tract of weanling pigs following black raspberry consumption

Many fruits are rich in anthocyanins (ACNs). ACNs have high antioxidant capacity, but because of their apparent low bioavailability, their possible roles in health promotion in vivo are still in question. The objectives of these studies were to determine the fate of ACNs within the gastrointestinal (GI) tract and the effect on the bioavailability and subsequent metabolism of ACNs. Five weanling pigs were fed freeze-dried black raspberry (Rubus occidentalis L.) powder by oral administration, which provided 1146.1 +/- 44.6 micromol TE of oxygen radical absorbance capacity with fluorescein as a fluorescent probe (ORAC(FL)) per kg and 50.5 +/- 3.7 mg per kg total ACNs. After 4 h, the pigs were sacrificed and the contents of five GI segments (duodenum, jejunum, ileum, cecum, and colon) were collected and analyzed for their total antioxidant capacity (TAC, measured as ORAC(FL)) and ACNs. The recoveries of TAC and total ACNs were 46.5 +/- 3.5 and 41.7 +/- 4.9%, respectively. Both total ACNs and TAC were recovered primarily in the ileum, cecum, and colon at 4 h after a meal. Cyanidin aglycone with different sugar moieties showed significant differences in their recovery within the GI tract with sambubiose > sambubiose-rhamnose = rutinose > glucose. Recovery of ACNs within the GI tract was positively and linearly associated with urinary ACN recovery, which suggests that stability within the GI tract and not decreased absorption accounts for the increased recovery. The environment of different segments of the GI tract may determine the stability of individual ACNs. Complex ACNs containing di- or triglycosides disappeared more slowly in the GI tract than simple ACNs such as a monoglycoside. TAC and total ACNs remained high 4 h after feeding, which indicates that ACNs provide significant antioxidant protection in the environment of the gut epithelium.     

Anthocyanin metabolism in rats and their distribution to digestive area, kidney, and brain

Anthocyanins are present in human diet due to their wide occurrence in fruits and beverages. They possess antioxidant activities and could be involved in several health effects. The aim of this study was to investigate anthocyanin metabolism and distribution in the digestive area organs (stomach, jejunum and liver) and kidney, as well as a target tissue (brain) in rats fed with a blackberry (Rubus fruticosus L.) anthocyanin-enriched diet for 15 days. Identification and quantification of anthocyanin metabolites was carried out by HPLC-ESI-MS-MS and HPLC-DAD, respectively. The stomach exhibited only native blackberry anthocyanins (cyanidin 3-O-glucoside and cyanidin 3-O-pentose), while in other organs (jejunum, liver, and kidney) native and methylated anthocyanins as well as conjugated anthocyanidins (cyanidin and peonidin monoglucuronides) were identified. Proportions of anthocyanin derivatives differed according to the organ considered, with the liver presenting the highest proportion of methylated forms. Jejunum and plasma also contained aglycone forms. In the brain, total anthocyanin content (blackberry anthocyanins and peonidin 3-O-glucoside) reached 0.25 +/- 0.05 nmol/g of tissue (n = 6). The urinary excretion of total anthocyanins was low (0.19 +/- 0.02% of the ingested amount). Thus, organs of the digestive area indicated a metabolic pathway of anthocyanins with enzymatic conversions (methylation and/or glucurono-conjugation). Moreover, following consumption of an anthocyanin-rich diet, anthocyanins enter the brain.     

Enhanced Heavy Metal Sorption by Surface-Oxidized Activated Carbon Does Not Affect the PAH Sequestration in Sediments

We examined the sorption of heavy metals and polycyclic aromatic hydrocarbons (PAHs) to surface-oxidized activated carbon (AC) and its effect on the distribution of those compounds in sediments. Created surface oxygen groups on AC enhanced the sorption of copper, which is superior in sorption competition, in the marine sediments. In case of cadmium, aqueous chemistry altered by AC addition, such as pH, has greater impact on the bioavailability according to the result of a sequential extraction combined with the pore water concentration measurements. Oxidized AC exhibited 2.3 times more adsorption of reduced bioavailable copper while 23% of bioavailable cadmium was adsorbed onto unmodified AC. No significant changes in BET surface area, pore volume, and AC/water distribution coefficient (K _AC) of PAHs were observed with surface-oxidized AC. The largest difference in K _AC after the oxidation was only 0.14 log unit. Consequently, freely dissolved aqueous concentrations of PAHs were reduced by more than 96% for all tested ACs in a week despite the increased Cu sorption on AC. This indicates that enhanced metal sorption by surface oxidation of AC is less significant in controlling bioavailability of PAHs in sediments than particle size or sorbent dose.     

Inhibition of gastrointestinal lipolysis by green tea, coffee, and gomchui (Ligularia fischeri) tea polyphenols during simulated digestion

Green tea, coffee, and gomchui (Ligularia fischeri) tea, which are rich in polyphenols, may exhibit antiobesity effects by inhibiting pancreatic lipase. However, the bioavailability of some polyphenols is poor due to either degradation or absorption difficulties in the gastrointestinal tract, thus making their beneficial effects doubtful. This study was conducted to evaluate the inhibitory effect of three beverages on lipolysis and the contribution of their major polyphenols during simulated digestion. During simulated digestion, gomchui tea was the most potent at inhibiting gastrointestinal lipolysis, whereas green tea was the least potent. The strongest lipase inhibitor among purified major polyphenols was a green tea polyphenol, (-)-epigallocatechin gallate (EGCG, IC(50) = 1.8 ± 0.57 μM), followed by di-O-caffeoylquinic acid isomers (DCQA, IC(50) from 12.7 ± 4.5 to 40.4 ± 2.3 μM), which are gomchui tea polyphenols. However, the stability of DCQA was greater than that of EGCG when subjected to simulated digestion. Taken together, gomchui tea, which has DCQA as the major polyphenol, showed stronger lipolysis inhibitory activity during simulated digestion compared to both green tea and coffee.     

Intestinal absorption of luteolin from peanut hull extract is more efficient than that from individual pure luteolin

Luteoin is one of the main flavones and the crucial effective component of peanut hull extract (PHE). The present paper aims to elucidate the absorption mechanism of luteolin and clarify whether its absorption occurs primarily at a specific site of the intestine by an in situ single-pass intestinal perfusion (SPIP) model. Moreover, the paper investigates the difference in absorption of luteolin when it is administered in PHE form and as pure luteolin by the SPIP model and in vivo pharmacokinetics studies. Results showed that the effective permeability ( P eff) and absorption rate constant ( k a) of pure luteolin(5.0 microg/mL) in duodenum and jejunum were not significantly different, but markedly higher than that in the colon and ileum. The P eff and k a of luteolin in jejunum were concentration-independent, and the ATP inhibitor (DNP) did not influence P eff and k a of pure luteolin. However, the P eff and k a of luteolin in PHE were significantly greater than that of pure luteolin. The pharmacokinetics study showed that following oral administration of a single dose of pure luteolin (14.3 mg/kg) or PHE (= 14.3 mg/kg of luteolin) in rats, the peak concentration of luteolin in plasma ( C max) and the area under the concentration curve (AUC) for pure luteolin were 1.97 +/- 0.15 microg/mL and 10.7 +/- 2.2 microg/mL.h, respectively. These parameters were significantly lower than those of the PHE group ( P < 0.05), C max = 8.34 +/- 0.98 microg/mL and AUC = 20.3 +/- 1.3 microg/mL.h, respectively. It can be concluded that luteolin is absorbed passively in the intestine of rats and that its absorption is more efficient in the jejunum and duodenum than in the colon and ileum. The bioavailability of luteolin in PHE form is significantly greater than that of pure luteolin.     

Iron and zinc absorption from two bean (Phaseolus vulgaris L.) genotypes in young women

Extrinsic and intrinsic iron and zinc labels were used to test iron and zinc absorption from two bean (Phaseolus vulgaris) genotypes, containing normal (common beans, CB) or higher (HFeZnB) iron and zinc concentrations, fed in single meals to young women with low iron reserves. The women were divided into two groups, with one receiving a CB test meal (n = 12) and the other, an HFeZnB test meal (n = 11). The beans were intrinsically labeled hydroponically with (55)Fe (CB and HFeZnB) and with (70)Zn (HFeZnB). Concentrations of zinc and iron were 98 and 65% higher, respectively, in HFeZnB as compared to CB, but phytic acid contents were similar. Extrinsic labels were (59)Fe (CB and HFeZnB), (67)Zn (CB), and (68)Zn (HFeZnB). Iron and zinc percent absorption levels were calculated from radio-iron activity in red blood cells and from urinary excretion of zinc isotopes. Intrinsic and extrinsic iron absorption measures were highly correlated (R (2) = 0.986) (average extrinsic/intrinsic ratio was 1.00). Iron absorption was low (geometric mean < 2%) in both bean types, and total iron absorbed was not different between types. Intrinsic zinc absorption from the HFeZn beans was higher than extrinsic absorption (15.2% vs 13.4%, p < 0.05) (average extrinsic/intrinsic was 0.90). The correlation between intrinsic and extrinsic zinc measures was not as high as that for iron (R (2) = 0.719). Percent zinc absorption levels were similar in both bean types, but total extrinsic zinc absorbed was 90% higher (p < 0.05) from the HFeZnB meal. Thus, the less expensive and time-consuming extrinsic labeling may be used to screen various varieties of beans for iron bioavailability in humans, but it underestimates zinc absorption by approximately 10%. Selective breeding for high-zinc bean genotypes may improve zinc status. However, high-iron genotypes appear to have little effect on iron status when fed alone in single meals to women with low iron reserves.     

Curcumin bioavailability from enriched bread: the effect of microencapsulated ingredients

Human bioavailability of curcumin from breads enriched with 1 g/portion of free curcumin (FCB), encapsulated curcumin (ECB), or encapsulated curcumin plus other polyphenols (ECBB) was evaluated. Parental and metabolized curcuminoids and phenolic acids were quantified by HPLC/MS/MS in blood, urine, and feces collected over 24 h. The concentrations of serum curcuminoids were always below 4 nmol/L and those of glucuronides 10-fold less. Encapsulation delayed and increased curcuminoid absorption as compared to the free ingredient. Serum and urinary concentrations of ferulic and vanillic acid were between 2- and 1000-fold higher than those of curcuminoids, with ECBB eliciting the highest amounts. Fecal curcuminoids were 6-fold more abundant after ECB than FCB, while phenolic acids after ECBB quadruplicated those after ECB. Curcuminoid encapsulation increased their bioavailability from enriched bread, probably preventing their biotransformation, with combined compounds slightly reducing this effect. Phenolic acids are the major metabolites of curcuminoids and may contribute to their biological properties.     

Absorption of anthocyanins from blueberry extracts by caco-2 human intestinal cell monolayers

Recent studies have shown that dietary polyphenols may contribute to the prevention of cardiovascular disease and cancer. Anthocyanins from different plant sources including blueberries have been shown to possess potential anticancer activities. One of the key factors needed to correctly relate the in vitro study results to human disease outcomes is information about bioavailability. The objectives of the current study were to evaluate the absorption of blueberry anthocyanin extracts using Caco-2 human intestinal cell monolayers and investigate the effects of different aglycones, sugar moieties, and chemical structure on bioavailability of different types of anthocyanins. The results of this study showed that anthocyanins from blueberries could be transported through the Caco-2 cell monolayers although the transport/absorption efficiency was relatively low compared to other aglycone polyphenols. The transport efficiency of anthocyanins averaged approximately 3-4% [less than 1% in delphinidin glucoside (Dp-glc)]. No significant difference in transport/absorption efficiency was observed among three blueberry cultivars. The observed trends among different anthocyanins generally agreed well with some published in vivo results. Dp-glc showed the lowest transport/absorption efficiency, and malvidin glucoside (Mv-glc) showed the highest transport/absorption efficiency. Our result indicates that more free hydroxyl groups and less OCH(3) groups can decrease the bioavailability of anthocyanins. In addition, cyanindin glucoside (Cy-glc) showed significantly higher transport efficiency than cyanidin galactoside (Cy-gal), and peonidin glucoside (Pn-glc) showed significantly higher transport efficiency than peonidin galactoside (Pn-gal), indicating that glucose-based anthocyanins have higher bioavailability than galactose-based anthocyanins.     

Absorption and bioavailability of artepillin C in rats after oral administration

Artepillin C (AC), an active ingredient of Brazilian propolis, permeates intact across Caco-2 cells by transcellular passive diffusion. The permeation of AC across Caco-2 cells is as efficient as that of phenolic acids and the microbial metabolites of poorly absorbed polyphenols, which are actively absorbed by the monocarboxylic acid transporter (MCT) (Biochim. Biophys. Acta 2005, 1713, 138-144). Here, the absorption of orally administered AC in rats has been studied to evaluate its pharmacokinetics and bioavailability in vivo in comparison with those of p-coumaric acid (CA), a substrate of MCT. Rats were given 100 micromol/kg of body weight of AC or CA, and blood was subsequently collected from the portal vein and abdominal artery. AC, CA, and their metabolites were quantified by coulometric detection using HPLC-ECD. The serum concentration of intact AC and CA in the portal vein peaked at 5-10 min after administration, with a C(max) of 19.7 micromol/L for AC and 74.8 micromol/L for CA. The area under the curve (AUC) for intact AC and CA in the portal vein was calculated from the serum concentration as 182.6 and 3057.3 micromol.min.L(-1), respectively. The absorption efficiency of CA was about 17-fold higher than that of AC. Furthermore, the bioavailability of CA was about 278-fold higher than that of AC, and the ratio of AUC in the abdominal artery to AUC in the portal vein was 0.04 and 0.70, for AC and CA, respectively. Thus, AC is likely to be more susceptible to hepatic elimination than is CA. The bioactive compound of AC in vivo should be investigated further.     

The stomach as a "bioreactor": when red meat meets red wine

To determine the stomach bioreactor capability for food oxidation or antioxidation, rats were fed red turkey meat cutlets (meal A) or red turkey meat cutlets and red wine concentrate (meal B). The hydroperoxides (LOOH) and malondialdehyde (MDA) levels of the stomach contents were evaluated during and after digestion; the postprandial plasma MDA level was also evaluated. In independently fed rats, the stomach LOOH concentration fell substantially 90 min following the meal, and the addition of red wine polyphenols enhanced LOOH reduction 3-fold. A similar trend was obtained for MDA. After pyloric ligation, the stomach contents of rats fed red meat homogenate showed >2-fold increases in LOOH and MDA accumulation. The postprandial plasma MDA level increased significantly by 50% following meal A and was maintained or even fell by 34% below basal level following meal B. The findings show that consumption of partially oxidized food could increase lipid peroxidation in the stomach and the absorption of cytotoxic lipid peroxidation products into the body. The addition of antioxidants such as red wine polyphenols to the meal may alter these outcomes. These findings explain the potentially harmful effects of oxidized fats in foods and the important benefit of consuming dietary polyphenols during the meal.     

Supplementation with grape seed polyphenols results in increased urinary excretion of 3-hydroxyphenylpropionic Acid, an important metabolite of proanthocyanidins in humans

Grape seed extract provides a concentrated source of polyphenols, most of which are proanthocyanidins. Polymeric proanthocyanidins are poorly absorbed in the small intestine of humans, and exposure may result from metabolism to phenolic acids by colonic bacteria. Any biological effects of proanthocyanidins may be due to the phenolic acid metabolites. Several phenolic acids have been identified as proanthocyanidin metabolites, but these may be derived from a range of other dietary sources. The aim of this study was to determine if 24-h urinary excretion of specific phenolic acids increased significantly and consistently following regular supplementation with grape seed extract. In a randomized, double-blind placebo-controlled trial, 69 volunteers received grape seed extract (1000 mg/day total polyphenols) or placebo for 6 weeks. Supplementation with grape seed polyphenols resulted in a consistent increase in the excretion of 3-hydroxyphenylpropionic acid (3-HPP, P < 0.001) and 4-O-methylgallic acid (P < 0.001) and a less consistent increase in the excretion of 3-hydroxyphenylacetic acid (P = 0.002). The observed increase in 3-HPP is in line with the suggestion that this compound is a major phenolic acid breakdown product of proanthocyanidin metabolism in vivo.     

The fate of trans-caftaric acid administered into the rat stomach

trans-Caftaric acid is the most abundant nonflavonoid phenolic compound in grapes and wines. It occurs in chicory and is one of the bioactive components of Echinacea purpurea. In order to fill the gap of knowledge about its bioavailability in mammals, we investigated its absorption, tissue distribution, and metabolism in rats. Assuming that the stomach is a relevant site of absorption of dietary polyphenols, a solution of trans-caftaric acid was maintained in the ligated stomach of anaesthetized rats for 20 min. Intact trans-caftaric acid was detected in rat plasma at both 10 and 20 min (293 +/- 45 and 334 +/- 49 ng/mL, respectively), along with its O-methylated derivative trans-fertaric acid, whose concentration rose over time (from 92 +/- 12 to 185 +/- 24 ng/mL). At 20 min, both trans-caftaric acid and trans-fertaric acid were detected in the kidney (443 +/- 78 and 2506 +/- 514 ng/g, respectively) but not in the liver. Only trans-fertaric acid was found in the urine (33.3 +/- 12.8 microg/mL). In some rats, trans-caftaric acid was detected in the brain (180 +/- 20 ng/g).     

Urolithins Are the Main Urinary Microbial-Derived Phenolic Metabolites Discriminating a Moderate Consumption of Nuts in Free-Living Subjects with Diagnosed Metabolic Syndrome

Walnuts ( Juglans regia L.), hazelnuts ( Corylus avellana L.), and almonds ( Prunus dulcis Mill.) are rich sources of ellagitannins and proanthocyanidins. Gut microbiota plays a crucial role in modulating the bioavailability of these high molecular weight polyphenols. However, to date there are no studies evaluating the capacity to produce nut phenolic metabolites in subjects with metabolic syndrome (MetS), a pathology associated with an altered gut bacterial diversity. This study applied a LC-MS targeted approach to analyze the urinary excretion of nut phenolic metabolites in MetS subjects following 12 weeks of nut consumption, compared to sex- and age-matched individuals given a nut-free control diet. Metabolites were targeted in both hydrolyzed and nonhydrolyzed urine by LC-PDA-QqQ-MS/MS analysis, and identification of metabolites lacking available standards was confirmed by LC-ESI-ITD-FT-MS. Ellagitannin-derived urolithins A and B significantly increased after the nut-enriched-diet, urolithins C and D were also detected, and a complex combination of urolithin-conjugated forms was observed in nonhydrolyzed urine, confirming an extensive phase II metabolism after absorption. In contrast, no significant increases in proanthocyanidin microbial metabolites were observed in urine following nut consumption. Because the intestinal microbiota of the subjects in this study could catabolize ellagitannins into a wide range of urolithins, further research is strongly warranted on the in vivo potential of these microbial metabolites in reducing cardiometabolic risk.